Just had the AC modifications done on our 96' by Capitol Hummer in Greenbelt, Md.

Some observations:

The new condenser is smaller but of a different design than the original. It seems to be made like a standard automotive radiator in that it does not have the usual pipe style arrangement with the pressed on fins. The passages are oval which should lower the air turbulence passing through the unit. The refrigerant capacity is a bit less but this should not be important since heat transfer to the air is the critical issue. I believe the high speed fan operates on the high pressure switch which means it won't operate say, in the winter when the AC is needed to dehumidify the interior. The outside air will be cool enough to keep the pressures down. After looking over the AC system, I think the problem was not capacity but design layout.

The condenser is the first item, oil coolers second, and finally the radiator. Since these items are pointed upward, the combined heat of the two lower devices will heat up the condenser, especially after driving and parking for a while. The hot sun bears down on top of the condenser at the same time the heat is rising from the other heat exchangers. When you start the vehicle, the fan has not sensed enough heat to engage the clutch fully so it free wheels. Result, not much cooling. As soon as you get up some speed, the air finally begins cooling things down enough for the condenser to begin carrying off the cabin heat. Oh yes, buy this time you are at a stop light and will have to wait until moving again for the AC to continue.

I do not think the standard condenser with fan add on will fit under the hood without extensive modifications and I mean extensive. Things like moving the entire assemblies closer to the fan, whew.

Make sure that you keep the factory original parts so you can re-fit them later if the condenser goes out in a few years. Who knows, by then a super low profile fan may be on the market that might work with the old condenser. You will need to fabricate a mounting assembly to support the fan since the condenser fins will be in the way.

One final note:

The mechanic at Capital Hummer called me in to show the recommended fan mounting arrangement. The instructions call for gently bending the new condenser so the existing holes will align correctly with the fan's bolt centers. He thought that this was, well, kind of disturbing since this new unit is not constructed using the old pipe and pressed on fin arrangement. He recommended that we use UV resistant ty-raps to attach the two fan mounting holes to the condenser and I agreed with him since the blade balance and fan weight were acceptable.

The modifications do work very well, especially after re-starting in a hot parking lot around mid day. No longer does one have to run in a lower gear hoping the fan thermostat will kick in, accelerating the cool-down process.

John W. Watkins Jr.
'96 Turbo Wagon

This is the AC modification using the smaller yet more efficient condenser from AM General. It does not use the tube and fin design but is more like a high pressure version of a typical radiator.

Now that it is getting hot - especially here in Texas and the South, I decided I would try and remedy my poor A/C performance. I called Overseas Motors and Lynch Hummer today and inquired about the kits used to upgrade the A/C on 1992-1996 model year Hummers. Those like me who have the 1994 model are so very fortunate because we already have the upsized condenser coil included in the other kits. That saves about $500 there alone. Installation at the dealer takes 2 to 2-1/2 of labor time. It looks as if it can be easily done with the exception of the refrigerant. I would recommend taking it o a professional to have the system evacuated.

The part number for the kits are:

05744670 for the 1992-1996 models 05744668 for the 1994 only models

The kits include:

The kits, as I understand it, are approx. $700-$750 for the 1992-1996 kit and $225-$250 for the 1994 kit.

Kevin Curry
Red '94 Hummer Fast-back

See also: Allan Madar's web page on this subject